Partial reinforcement and context switch effects in human predictive learning

Human participants were trained in a trial-by-trial contingency judgements task in which they had to predict the probability of an outcome (diarrhoea) following different cues (food names) in different contexts (restaurants). Cue P was paired with the outcome on half of the trials (partial reinforcement), while cue C was paired with the outcome on all the trials (continuous reinforcement), both cues in Context A. Test was conducted in both Context A and a different but equally familiar context (B). Context change decreased judgements to C, but not to P (Experiment 1). This effect was found only in the cue trained in the context where a different cue was partially reinforced (Experiment 2). Context switch effects disappeared when different cues received partial reinforcement in both contexts of training (Experiment 3). The implications of these results for an explanation of context switch effects in terms of ambiguity in the meaning of the cues prompting attention to the context (e.g., Bouton, 1997) are discussed.     

Inhibitory tagging in an interrupted visual search

Inhibition of return facilitates visual search, biasing attention away from previously examined locations. Prior research has shown that, as a result of inhibitory tags associated with rejected distractor items, observers are slower to detect small probes presented at these tagged locations than they are to detect probes presented at locations that were unoccupied during visual search, but only when the search stimuli remain visible during the probe-detection task. Using an interrupted visual search task, in which search displays alternated with blank displays, we found that inhibitory tagging occurred in the absence of the search array when probes were presented during these blank displays. Furthermore, by manipulating participants’ attentional set, we showed that these inhibitory tags were associated only with items that the participants actively searched. Finally, by probing before the search was completed, we also showed that, early in search, processing at distractor locations was actually facilitated, and only as the search progressed did evidence for inhibitory tagging arise at those locations. These results suggest that the context of a visual search determines the presence or absence of inhibitory tagging, as well as demonstrating for the first time the temporal dynamics of location prioritization while search is ongoing.     

Children''s understanding of belief and disconfirming visual evidence

Data from 3- to 5-year-old children show that even the youngest have an understanding that a story character cannot think an object is in a box when the character looks into the empty box. This understanding is, however, limited to the case where children share the same visual perspective with the character. When visual perspectives are different the relevant knowledge develops shortly after 4 years at about the time that children master the false belief task. These results are interpreted as young children using an implicit constraint that “think” cannot be applied in view of disconfirming visual evidence. This implicit knowledge becomes explicit and, thus, perspective independent with some delay.     

Cholinergic septo-hippocampal innervation is required for trace eyeblink classical conditioning

We studied the effects of a selective lesion in rats, with 192-IgG-saporin, of the cholinergic neurons located in the medial septum/diagonal band (MSDB) complex on the acquisition of classical and instrumental conditioning paradigms. The MSDB lesion induced a marked deficit in the acquisition, but not in the retrieval, of eyeblink classical conditioning using a trace paradigm. Such a deficit was task-selective, as lesioned rats were able to acquire a fixed-interval operant conditioning as controls, and was not due to nonspecific motor alterations, because spontaneous locomotion and blink reflexes were not disturbed by the MSDB lesion. The deficit in the acquisition of a trace eyeblink classical conditioning was reverted by the systemic administration of carbachol, a nonselective cholinergic muscarinic agonist, but not by lobeline, a nicotinic agonist. These results suggest a key role of muscarinic denervation on the acquisition of new motor abilities using trace classical conditioning procedures. It might also be suggested that muscarinic agents would be useful for the amelioration of some associative learning deficits observed at early stages in patients with Alzheimer's disease.     

Defensive emotions and evaluative judgements: Sensitivity to anger and fear predicts moral judgements,whereas sensitivity to disgust predicts aesthetic judgements

Aesthetic and moral evaluations engage appetitive and defensive emotions. While the role played by pleasure in positive aesthetic and moral judgements has been extensively researched, little is known about how defensive emotions influence negative aesthetic and moral judgements. Specifically, it is unknown which defensive emotions such judgements tap into, and whether both kinds of judgement share a common emotional root. Here, we investigated how participants' individual sensitivity to disgust, fear, anger and sadness predicted subjective judgements of aesthetic and moral stimuli. Bayesian modelling revealed that participants who were more sensitive to anger and fear found conventional and moral transgressions more wrong. In contrast, participants who were more sensitive to disgust disliked asymmetrical geometric patterns and untidy rooms more. These findings suggest that aesthetic and moral evaluations engage multiple defensive emotions, not just disgust, and that they may rely on different defensive emotions as part of their computational mechanism.     

Context change and retention interval can have additive, rather than interactive, effects after taste aversion extinction

Spontaneous forgetting is often attributed to retrieval failure caused by natural changes in the background context that occur over time. However, some investigators have argued that the context-change account of forgetting is paradoxical, because context-change effects themselves decrease over time. To resolve the paradox, we have suggested that organisms may merely forget the physical context as the temporal context in which it is embedded changes; this explanation accepts a fundamental similarity between time and physical context. The present experiment tested an implication of this analysis by examining the interaction between retention interval and context change in rats after a taste aversion was conditioned and then extinguished. Importantly, subjects tested at the longer (24-day) retention interval received reminder exposure to the physical contexts before testing. Under these conditions, retention interval and context change both caused relapse of the extinguished aversion (spontaneous recovery and renewal, respectively), and the strongest overall relapse was observed when the two treatments were combined. Such additivity (rather than interactivity) is consistent with a context-change account of forgetting and sets the stage for resolution of the context-forgetting paradox.     

The diversity principle in the testing of arguments

According to the diversity principle of scientific reasoning, hypotheses receive greater confirmation when they are supported by diverse rather than similar sets of data. This article examines whether people reason like intuitive scientists by conforming to the diversity principle in the testing of arguments. The results of two experiments demonstrate that people do indeed conform to the diversity principle by choosing a set of diverse rather than similar premises to test the conclusion of an argument. These findings are discussed in terms of the different reasoning processes involved in argument evaluation, argument testing, and rule discovery.     

ARTIFICIAL INTELLIGENCE AND DE LAS CASAS: A 1492 RESONANCE

Abstract. A comparison is made between two unlikely debates over intelligence. One debate took place in 1550 at Valladolid, Spain, between Bartolomé de las Casas and Juan Gines de Sepúlveda over the intelligence of the Amerindian. The other debate is contemporary, between John Searle and various representatives of the "strong" artificial intelligence (AI) community over the adequacy of the Turing test for intelligence. Although the contemporary debate has yet to die down, the Valladolid debate has been over for four hundred years. The question asked here is whether the contemporary debate can profit from the previous one. The common bond providing the basis for contrast is the issue of the "other" which is present in both debates. From this contrast, the observation is made that the question of meaning is intimately tied to the question of intelligence.     

Character strengths: a study of Argentinean soldiers

The primary objective of this research was to study the differences in positive traits between military and civilian college students and between cadets in their first and final years at a military academy. Second, the research aimed to study the relations between positive traits and the academic and military performance of cadets in their first and final years, according to the classification of positive traits by Peterson and Seligman (2004). To accomplish these objectives, a sample of university students from a military educational institution and a sample of civilian university students were studied. The instruments used were a 24-item self-report measure of positive traits, a measure of social desirability, and objective scores of academic and military performance. The results generally showed that when age and career stage were held constant, the scores of the military students were higher than the scores of the civilian students across various strengths. Military students reported higher levels of the character strength of spirituality than did civilian students. The relationships between strengths and performance differed for students in their first and final years at the military academy. In particular, cadets with the higher levels of academic or military performance in their last year, i.e., the cadets best adapted to the academy, reported higher levels of the character strength of persistence when compared to low-performing cadets in the same year of study.